1. Field of the Invention
The present invention is directed to a hand-held portable tool for pretinning the end portion of a tube member that includes a source of ultrasonic energy and a tank portion for containing a bath of molten metal. In use, a tube end portion to be coated or pretinned with a layer of metal is arranged in the tank with ultrasonic energy source in intimate contact with the tube member so that the ultrasonic energy is transmitted to the end portion to cause the oxide to be scrubbed off and the surface coated with a layer of metal.
2. Description of the Prior Art
In manufacturing heat exchangers for use in refrigeration systems, it is customary to assemble them as a unit and then, at some later time, connect them to the other components of the refrigeration system. Generally, heat exchange assemblies lend themselves effectively to mass or automatic production techniques in that many of the joints such as return bends may be joined at the same time. However, the tube ends connecting the heat exchangers to the other components of the refrigeration system remain to be done individually and, accordingly, is usually a tedious time-consuming operation.
In preparing the tube end portions to be joined it is necessary to effect a complete removal of oxide from the surfaces to be joined. One method of effectively removing the oxide is in the presence of a molten alloy by means of an ultrasonic soldering pot, such as the one disclosed in U.S. Pat. No. 3,762,368-Struhe et al. Generally, an object to be cleaned of oxide and coated is placed in an alloy bath held in a container. A transducer is utilized to permeate the alloy with ultrasonic waves to cause cavitation which provide a good cleaning and coating action on the surface to be joined.
The use of the ultrasonic coating or joining is attractive when employed in mass or quantity production of heat exchangers where a plurality of parts may be arranged so as to be immersed in the alloy at the same time and coated or joined simultaneously. This is especially true when heat exchangers having return bends are to be assembled, wherein, the return bends are placed on the appropriate tube ends and the entire end portion including the return bends are immersed, as for example, in the ultrasonic soldering pot of the Struhe et al patent and accordingly all of the joints are made simultaneously.
In connecting the completed heat exchanger assembly to the other components necessary to complete the refrigeration system, the use of a soldering pot is generally not possible. This is especially true when the tube ends to be coated or joined to other components of the refrigeration system are so arranged and located on the heat exchanger that a substantial portion of the heat exchanger may have to be immersed in the alloy together with the selected portion. Generally this results not only in the excessive use of coating material but the entire heat exchanger assembly must be manipulated each time a portion is to be coated or joined.